The invention is directed to product display cabinets or cases which are used in self-service markets, stores, and other establishments in which products are displayed, viewed, selected and purchased. Such display cabinets generally operate below external ambient temperature. Typically such display cabinets include one or more glass paneled doors through which products on shelves in an interior compartment of the display case can be viewed.
Typically the closures or doors for such display cabinets include an insulated glass unit or assembly comprised of a plurality of glass panes disposed in substantially parallel side-by-side spaced relationship to each other. Normally spacers maintain the glass panes separated from each other and a peripheral seal unites the assembly into a unitized glass unit. Door frames for such glass units have been conventionally formed in many different ways. In accordance with U.S. Pat. No. 3,673,735 issued on Jul. 4, 1972 to Winsler et al., a door frame is made from a plurality of rectangularly related extrusions made from aluminum or some other suitable metal. Four pieces cut from one specific extrusion are mitered at the corners and are welded together to form an outer frame member, as are four pieces of a different extrusion to form an inner frame member, both of a generally open polygonal annular configuration. Obviously, such door frames are undesirable for use in refrigerated display cases because of the high heat conductivity of metal. More recently metal frames remain utilized in association with display doors for refrigerated display cases, but thermal insulating barrier members formed of molded, expanded or extruded plastic material are placed against the insulated glass unit to increase efficiency because the barrier members have relatively low heat conductivity. However, discounting use of a conventional peripheral gasket member, such display doors still utilize a metallic door frame made of four pieces of extruded metal mitered at the corners and welded to each other resulting in decreased heat conductivity, but increased production costs. Even in the case of a refrigerator door formed from polymeric material, such as disclosed in the patent to Richardson et al. granted on Jun. 8, 1999 under U.S. Pat. No. 5,910,083, the top, bottom and side rail elements are mitered at the corners and united thereat by bonding to form a generally polygonal annular door frame. However, for the most part such conventional insulated display cabinet doors are extremely complex in the manufacture and assembly thereof resulting in relatively high prices per door at both wholesale and retail levels.
Conventional doors for refrigerated display cabinets also generally carry upper and lower outwardly spring-biased pivot pins which enter pivot openings in the door frame of an associated display cabinet. Insulated doors are relatively heavy and aligning and inserting the pivot pins into the pivot openings can be difficult, particularly when the pivot pins are under relatively high biasing forces.